Die head of screw-cutitng machines



c. w. HARRIS. DIE HEAD OF SCREW CUTTl NG MACHINES.

APPLICATION FILED APR. 17, I920.

Patented May 30; 1922.

2 SHEETS-SHEET 1.

' c. w. HARRIS;

DIE HEAD OF SCREW CUT T|NG MACHI NES. APPLICATION FILED APR. 17. 1920.

1,417,601. Patented May30, 1922.

. lfilfiiiililllll ullllllliiiilill CLAUDE WILLIAM HARRIS, or LEVENSHULME, MANcHnsr'nn, ENGLAND.

rare e DIE HEAD or asm-enemas ivuronriv'n's.

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Specification of Letters Pate'nt. i Mi y.

Application filed'April 17, 19210. Serial no. 374,775.

T 0 all whom it may concern Be it known that I, CLAUDE VVILLIAM' Hana ject of the of Great Britainand Ireland, and resident of Levenshulme, liIanc-hester, England, haveinvented certain new and useful Improvements in the Die Heads of Screw-Cutting Machines, of which the following is a specification. I y I These iniprovements refer to the die heads of screw-cutting machines and relate, in particular, to die heads of the kind comprising a rotary head part and a series of pivoted holders, each of such holders being adapted to hold die 'or chaser, and each being movable about its. pivot so as toallow the'cut- I ting end of the chaser to approach or recedefrom the work in thearc of. a circle. In

such construction ofdie head jth'e holders used for holding the chasers for cutting a right hand thread are not adapted for use in holding the chasers for cutting'a left hand thread, and therefore two sets of holders are necessary. v

These improvements have for their object,

and consist primarily in providing adiehead-in which one set of holders serve for both right and left hand threads.

A further object and feature of the improvements is a compact and simple construction of die headas a whole.includi1ig means for readily adjusting the dies to and from the work;

Upon the accompanying drawings,

Fig. 1 illustrates a face oryend view, and

Fig. 2 a part longitudinal section and part side exterior elevation of a die-head. constructed according to the present invention.

Fig. 3 illustrates a face view of the die carrier alone.

Fig. 4 illustrates a face view.

Fig. 5 an edge view, and

Fig. 6 a longitudinal section of one of the die-holders.separate from the die head.

As shown, the improved die-head comprises the usual hollow shaft a to the flanged end a of which is bolted the die-carrier plate 6, see Fig. 3, by stud bolts 6 see Fig. 2. Rotataloly surrounding the said flange a and die-carrier plate Z) is the cam ring 0, which is into which project rollers e on studs f,ca1"-' ried by the endwise niovablesleevejg.

In the die-carrier plate 6 fare"fourtholes If, 5 Zr, 6 and iii-each of suchh-oles isyar; ranged a tightlyefitting bush-'6 see jFigia Within each bush is mounted a stud bolt I)? which projects beyon'dr-the face of the die carrier plate. Upon the,projecting part of each bolt is mounted one of the di'e holder I plates it, a nut it the bolt.

As aforesaid, each die-holder plate 71, is of substantially triangular shape in outline, see F 1g. 1-, and-in one with said plateis adie holder 2', said holder heing fornle'd byftwo prqectin'gflanges, see Figs. 4- :and 5;;pro ducing between them; an open-ended. slot or recess for the reception Of t/he die-chaser, which is held in the slot or recess by ac ove r i, see Fig. 2. -Usually thechaser will be'hev elled on itsrear face and along one edge-and engaging such bevelled part will -b'era' weclgelike rib i aon the cover, whielrwill serve to firmly hold the chaser in p'os 'l'tioiiivl ifen' the cover is tightenedup bythe set screw i 5 As' slrown in Figs. 1 and 4, each "die-holder 72. has four holes if, h y/3, and it By ine'a-ns of the hole "7& or if t lre is a'da'pted' to fit one of the stud bolts 6 V i F or cutting a right-handthreaielthe {hole its in eachdie holder plate will be caus'edto engage one of. the stud bolts 6 iv-h-ils'tfor cutting'a left han'd'thre'a d the hole-Jt 'avill' be caused to engage sa i'd stud bolt; Ineach" case the die-holder will serve to hold the chaser at a tangent to the periphery of the work to be screw threaded. In one or other of the other holes if, it is fitted a stud 7' which is held to the plate by a nut j and which, behind the plate, carries a bowl or runner designed to lie in the groove c of the cam ring 0.

The flange forming each die holder screw threaded to receive the screw 72 for following'up the chaser as it wears away, and for holding it firmly to the work.

The chasers are composed of bars of steel grooved on one face to form the chaser teeth. With the holes it if. for the stud on the die carrier lying to right and left'of the longitudinal axis of the die-holder, said axis, even with the smallest diameter of work, will lie considerably out of parallel with a line drawn through the centre of thework and the centre of the stud about'which the serving to hold the plate on so? I of the carrier plate 7).;-

I out of contact with the work, the die-carrier plate 6 is formed on its periphery with recesses 6 see Fig. 3, the bowl passing into one or other of such recesses on the cam ring rotating to move the chaser i to contact with work of small diameter.

The operation ofthe device will be as folv lows: The bar or work to be screw threaded is held in a work holder so as to be incapable of rotation and said work is advanced to the cutter head. Assuming the die holders i to be set for cutting a right hand thread, i. e.: the holes 72? engaging the studs 5 and the studs j in the holes IL with the bowls thereon lying in the slots in the cam plate 0. The

.tubular sleeve 9 is then moved horizontally by any convenient means (not shown). During this movement the bowl 6 slides in the inclined slot (Z and imparts a part rotary movement to the cam ring 0, the slots 0 in which are so shaped as to cause the die holders to converge with the cutters in the operative position. A reverse movement of the tubular'sleeve 9 causes the cutter to diverge in amanner which will be obvious from the foregoing description.

What I claim is I 1. A rotary die head suitable for cutting both right and left hand screw threads comprising a hollow spindle, a holder carrier plate rigidly attached to the spindle; a series of die holders each formed with two piVOt hearings to right and left of the tool respectively, a stud to, connect each die holder to the holder carrier, a slotted cam ring rotatably mounted on the spindle, a projection at the rear of each die holder capable of being attached to one of-two positions thereon and means to impart rotary movement to the cam ring, thearrangement being such that each die holder can be swivelled to positions to right and left of aline drawn through the axis of the die head and the pivot of the holder, and each also adapted to hold a die or chaser and allow of such die .or chaser being reversed, substantially as herein set forth. I

2. In die-heads of screw-cutting machines and of the kind herein referred to, a dieholder mounted upon a plate and said plate adapted to be pivotally'mounted upon the die-carrier, a cam ring rotatably mounted relatively to the die carrier the arrangement being such that the die-holder and'plate serve to carry the chaser and, in conjunction with such holes on one of a series of studs on the die-carrier plate, said holes lying respectively to right and left of the die-holder, and c said die-holder and die-holder plate having two further holes to either .of which a stud and bowl may be fitted and a grooved cam. ring said bowl lying in the groove ofthe cam ring, substantially as and for the purpose herein set forth.

In. witness whereof I have hereunto set my hand in the presence of a witness.

CLAUDE WILLIAM HARRIS.

lVitness HY. J UNGA. 

